In an angle detection apparatus for a rotation axis of a motor or the like, an amplitude-modulated signal of an excitation signal output from a resolver in accordance with a rotation angle is frequently used. In the angle detection apparatus using the resolver, the resolver is relatively expensive and the excitation signal is needed. Thus, an angle detection apparatus using an angle detection sensor, such as a Hall sensor, that is relatively inexpensive and does not need any excitation signal is beginning to be used more frequently.
In an angle detection apparatus, there is a problem that the angle accuracy is reduced when an offset is contained in an input. In addition, the angle detection apparatus using the resolver alone or the angle detection apparatus using the angle detection sensor alone cannot be applied to various uses. Accordingly, an angle detection apparatus capable of appropriately using either a resolver or an angle detection sensor depending on the use has been desired.